// InflaterInputStream.cs
//
// Copyright (C) 2001 Mike Krueger
// Copyright (C) 2004 John Reilly
//
// This file was translated from java, it was part of the GNU Classpath
// Copyright (C) 2001 Free Software Foundation, Inc.
//
// This program is free software; you can redistribute it and/or
// modify it under the terms of the GNU General Public License
// as published by the Free Software Foundation; either version 2
// of the License, or (at your option) any later version.
//
// This program is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
// GNU General Public License for more details.
//
// You should have received a copy of the GNU General Public License
// along with this program; if not, write to the Free Software
// Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA  02111-1307, USA.
//
// Linking this library statically or dynamically with other modules is
// making a combined work based on this library.  Thus, the terms and
// conditions of the GNU General Public License cover the whole
// combination.
// 
// As a special exception, the copyright holders of this library give you
// permission to link this library with independent modules to produce an
// executable, regardless of the license terms of these independent
// modules, and to copy and distribute the resulting executable under
// terms of your choice, provided that you also meet, for each linked
// independent module, the terms and conditions of the license of that
// module.  An independent module is a module which is not derived from
// or based on this library.  If you modify this library, you may extend
// this exception to your version of the library, but you are not
// obligated to do so.  If you do not wish to do so, delete this
// exception statement from your version.

using System;
using System.IO;
using System.Security.Cryptography;
#if !NETCF_1_0
#endif

namespace TidyBackups.SharpZipLib.Zip.Compression.Streams
{
    /// <summary>
    /// An input buffer customised for use by <see cref="InflaterInputStream"/>
    /// </summary>
    /// <remarks>
    /// The buffer supports decryption of incoming data.
    /// </remarks>
    public class InflaterInputBuffer
    {
        #region Constructors

        /// <summary>
        /// Initialise a new instance of <see cref="InflaterInputBuffer"/> with a default buffer size
        /// </summary>
        /// <param name="stream">The stream to buffer.</param>
        public InflaterInputBuffer(Stream stream) : this(stream, 4096)
        {
        }

        /// <summary>
        /// Initialise a new instance of <see cref="InflaterInputBuffer"/>
        /// </summary>
        /// <param name="stream">The stream to buffer.</param>
        /// <param name="bufferSize">The size to use for the buffer</param>
        /// <remarks>A minimum buffer size of 1KB is permitted.  Lower sizes are treated as 1KB.</remarks>
        public InflaterInputBuffer(Stream stream, int bufferSize)
        {
            inputStream = stream;
            if (bufferSize < 1024)
            {
                bufferSize = 1024;
            }
            rawData = new byte[bufferSize];
            clearText = rawData;
        }

        #endregion

        /// <summary>
        /// Get the length of bytes bytes in the <see cref="RawData"/>
        /// </summary>
        public int RawLength
        {
            get { return rawLength; }
        }

        /// <summary>
        /// Get the contents of the raw data buffer.
        /// </summary>
        /// <remarks>This may contain encrypted data.</remarks>
        public byte[] RawData
        {
            get { return rawData; }
        }

        /// <summary>
        /// Get the number of useable bytes in <see cref="ClearText"/>
        /// </summary>
        public int ClearTextLength
        {
            get { return clearTextLength; }
        }

        /// <summary>
        /// Get the contents of the clear text buffer.
        /// </summary>
        public byte[] ClearText
        {
            get { return clearText; }
        }

        /// <summary>
        /// Get/set the number of bytes available
        /// </summary>
        public int Available
        {
            get { return available; }
            set { available = value; }
        }

        /// <summary>
        /// Call <see cref="Inflater.SetInput(byte[], int, int)"/> passing the current clear text buffer contents.
        /// </summary>
        /// <param name="inflater">The inflater to set input for.</param>
        public void SetInflaterInput(Inflater inflater)
        {
            if (available > 0)
            {
                inflater.SetInput(clearText, clearTextLength - available, available);
                available = 0;
            }
        }

        /// <summary>
        /// Fill the buffer from the underlying input stream.
        /// </summary>
        public void Fill()
        {
            rawLength = 0;
            int toRead = rawData.Length;

            while (toRead > 0)
            {
                int count = inputStream.Read(rawData, rawLength, toRead);
                if (count <= 0)
                {
                    if (rawLength == 0)
                    {
                        throw new SharpZipBaseException("Unexpected EOF");
                    }
                    break;
                }
                rawLength += count;
                toRead -= count;
            }

#if !NETCF_1_0
            if (cryptoTransform != null)
            {
                clearTextLength = cryptoTransform.TransformBlock(rawData, 0, rawLength, clearText, 0);
            }
            else 
#endif
            {
                clearTextLength = rawLength;
            }

            available = clearTextLength;
        }

        /// <summary>
        /// Read a buffer directly from the input stream
        /// </summary>
        /// <param name="buffer">The buffer to fill</param>
        /// <returns>Returns the number of bytes read.</returns>
        public int ReadRawBuffer(byte[] buffer)
        {
            return ReadRawBuffer(buffer, 0, buffer.Length);
        }

        /// <summary>
        /// Read a buffer directly from the input stream
        /// </summary>
        /// <param name="outBuffer">The buffer to read into</param>
        /// <param name="offset">The offset to start reading data into.</param>
        /// <param name="length">The number of bytes to read.</param>
        /// <returns>Returns the number of bytes read.</returns>
        public int ReadRawBuffer(byte[] outBuffer, int offset, int length)
        {
            if (length < 0)
            {
                throw new ArgumentOutOfRangeException("length");
            }

            int currentOffset = offset;
            int currentLength = length;

            while (currentLength > 0)
            {
                if (available <= 0)
                {
                    Fill();
                    if (available <= 0)
                    {
                        return 0;
                    }
                }
                int toCopy = Math.Min(currentLength, available);
                Array.Copy(rawData, rawLength - available, outBuffer, currentOffset, toCopy);
                currentOffset += toCopy;
                currentLength -= toCopy;
                available -= toCopy;
            }
            return length;
        }

        /// <summary>
        /// Read clear text data from the input stream.
        /// </summary>
        /// <param name="outBuffer">The buffer to add data to.</param>
        /// <param name="offset">The offset to start adding data at.</param>
        /// <param name="length">The number of bytes to read.</param>
        /// <returns>Returns the number of bytes actually read.</returns>
        public int ReadClearTextBuffer(byte[] outBuffer, int offset, int length)
        {
            if (length < 0)
            {
                throw new ArgumentOutOfRangeException("length");
            }

            int currentOffset = offset;
            int currentLength = length;

            while (currentLength > 0)
            {
                if (available <= 0)
                {
                    Fill();
                    if (available <= 0)
                    {
                        return 0;
                    }
                }

                int toCopy = Math.Min(currentLength, available);
                Array.Copy(clearText, clearTextLength - available, outBuffer, currentOffset, toCopy);
                currentOffset += toCopy;
                currentLength -= toCopy;
                available -= toCopy;
            }
            return length;
        }

        /// <summary>
        /// Read a <see cref="byte"/> from the input stream.
        /// </summary>
        /// <returns>Returns the byte read.</returns>
        public int ReadLeByte()
        {
            if (available <= 0)
            {
                Fill();
                if (available <= 0)
                {
                    throw new ZipException("EOF in header");
                }
            }
            byte result = rawData[rawLength - available];
            available -= 1;
            return result;
        }

        /// <summary>
        /// Read an <see cref="short"/> in little endian byte order.
        /// </summary>
        /// <returns>The short value read case to an int.</returns>
        public int ReadLeShort()
        {
            return ReadLeByte() | (ReadLeByte() << 8);
        }

        /// <summary>
        /// Read an <see cref="int"/> in little endian byte order.
        /// </summary>
        /// <returns>The int value read.</returns>
        public int ReadLeInt()
        {
            return ReadLeShort() | (ReadLeShort() << 16);
        }

        /// <summary>
        /// Read a <see cref="long"/> in little endian byte order.
        /// </summary>
        /// <returns>The long value read.</returns>
        public long ReadLeLong()
        {
            return (uint) ReadLeInt() | ((long) ReadLeInt() << 32);
        }

#if !NETCF_1_0
        /// <summary>
        /// Get/set the <see cref="ICryptoTransform"/> to apply to any data.
        /// </summary>
        /// <remarks>Set this value to null to have no transform applied.</remarks>
        public ICryptoTransform CryptoTransform
        {
            set
            {
                cryptoTransform = value;
                if (cryptoTransform != null)
                {
                    if (rawData == clearText)
                    {
                        if (internalClearText == null)
                        {
                            internalClearText = new byte[rawData.Length];
                        }
                        clearText = internalClearText;
                    }
                    clearTextLength = rawLength;
                    if (available > 0)
                    {
                        cryptoTransform.TransformBlock(rawData, rawLength - available, available, clearText,
                                                       rawLength - available);
                    }
                }
                else
                {
                    clearText = rawData;
                    clearTextLength = rawLength;
                }
            }
        }
#endif

        #region Instance Fields

        private int rawLength;
        private readonly byte[] rawData;

        private int clearTextLength;
        private byte[] clearText;
#if !NETCF_1_0
        private byte[] internalClearText;
#endif

        private int available;

#if !NETCF_1_0
        private ICryptoTransform cryptoTransform;
#endif
        private readonly Stream inputStream;

        #endregion
    }

    /// <summary>
    /// This filter stream is used to decompress data compressed using the "deflate"
    /// format. The "deflate" format is described in RFC 1951.
    ///
    /// Author of the original java version : John Leuner.
    /// </summary>
    public class InflaterInputStream : Stream
    {
        #region Constructors

        /// <summary>
        /// Create an InflaterInputStream with the default decompressor
        /// and a default buffer size of 4KB.
        /// </summary>
        /// <param name = "baseInputStream">
        /// The InputStream to read bytes from
        /// </param>
        public InflaterInputStream(Stream baseInputStream)
            : this(baseInputStream, new Inflater(), 4096)
        {
        }

        /// <summary>
        /// Create an InflaterInputStream with the specified decompressor
        /// and a default buffer size of 4KB.
        /// </summary>
        /// <param name = "baseInputStream">
        /// The source of input data
        /// </param>
        /// <param name = "inf">
        /// The decompressor used to decompress data read from baseInputStream
        /// </param>
        public InflaterInputStream(Stream baseInputStream, Inflater inf)
            : this(baseInputStream, inf, 4096)
        {
        }

        /// <summary>
        /// Create an InflaterInputStream with the specified decompressor
        /// and the specified buffer size.
        /// </summary>
        /// <param name = "baseInputStream">
        /// The InputStream to read bytes from
        /// </param>
        /// <param name = "inflater">
        /// The decompressor to use
        /// </param>
        /// <param name = "bufferSize">
        /// Size of the buffer to use
        /// </param>
        public InflaterInputStream(Stream baseInputStream, Inflater inflater, int bufferSize)
        {
            if (baseInputStream == null)
            {
                throw new ArgumentNullException("baseInputStream");
            }

            if (inflater == null)
            {
                throw new ArgumentNullException("inflater");
            }

            if (bufferSize <= 0)
            {
                throw new ArgumentOutOfRangeException("bufferSize");
            }

            this.baseInputStream = baseInputStream;
            inf = inflater;

            inputBuffer = new InflaterInputBuffer(baseInputStream, bufferSize);
        }

        #endregion

        /// <summary>
        /// Get/set flag indicating ownership of underlying stream.
        /// When the flag is true <see cref="Close"/> will close the underlying stream also.
        /// </summary>
        /// <remarks>
        /// The default value is true.
        /// </remarks>
        public bool IsStreamOwner
        {
            get { return isStreamOwner; }
            set { isStreamOwner = value; }
        }

        /// <summary>
        /// Returns 0 once the end of the stream (EOF) has been reached.
        /// Otherwise returns 1.
        /// </summary>
        public virtual int Available
        {
            get { return inf.IsFinished ? 0 : 1; }
        }

        /// <summary>
        /// Skip specified number of bytes of uncompressed data
        /// </summary>
        /// <param name ="count">
        /// Number of bytes to skip
        /// </param>
        /// <returns>
        /// The number of bytes skipped, zero if the end of 
        /// stream has been reached
        /// </returns>
        /// <exception cref="ArgumentOutOfRangeException">
        /// <paramref name="count">The number of bytes</paramref> to skip is less than or equal to zero.
        /// </exception>
        public long Skip(long count)
        {
            if (count <= 0)
            {
                throw new ArgumentOutOfRangeException("count");
            }

            // v0.80 Skip by seeking if underlying stream supports it...
            if (baseInputStream.CanSeek)
            {
                baseInputStream.Seek(count, SeekOrigin.Current);
                return count;
            }
            else
            {
                int length = 2048;
                if (count < length)
                {
                    length = (int) count;
                }

                var tmp = new byte[length];
                int readCount = 1;
                long toSkip = count;

                while ((toSkip > 0) && (readCount > 0))
                {
                    if (toSkip < length)
                    {
                        length = (int) toSkip;
                    }

                    readCount = baseInputStream.Read(tmp, 0, length);
                    toSkip -= readCount;
                }

                return count - toSkip;
            }
        }

        /// <summary>
        /// Clear any cryptographic state.
        /// </summary>		
        protected void StopDecrypting()
        {
#if !NETCF_1_0
            inputBuffer.CryptoTransform = null;
#endif
        }

        /// <summary>
        /// Fills the buffer with more data to decompress.
        /// </summary>
        /// <exception cref="SharpZipBaseException">
        /// Stream ends early
        /// </exception>
        protected void Fill()
        {
            inputBuffer.Fill();
            inputBuffer.SetInflaterInput(inf);
        }

        #region Stream Overrides

        /// <summary>
        /// Gets a value indicating whether the current stream supports reading
        /// </summary>
        public override bool CanRead
        {
            get { return baseInputStream.CanRead; }
        }

        /// <summary>
        /// Gets a value of false indicating seeking is not supported for this stream.
        /// </summary>
        public override bool CanSeek
        {
            get { return false; }
        }

        /// <summary>
        /// Gets a value of false indicating that this stream is not writeable.
        /// </summary>
        public override bool CanWrite
        {
            get { return false; }
        }

        /// <summary>
        /// A value representing the length of the stream in bytes.
        /// </summary>
        public override long Length
        {
            get { return inputBuffer.RawLength; }
        }

        /// <summary>
        /// The current position within the stream.
        /// Throws a NotSupportedException when attempting to set the position
        /// </summary>
        /// <exception cref="NotSupportedException">Attempting to set the position</exception>
        public override long Position
        {
            get { return baseInputStream.Position; }
            set { throw new NotSupportedException("InflaterInputStream Position not supported"); }
        }

        /// <summary>
        /// Flushes the baseInputStream
        /// </summary>
        public override void Flush()
        {
            baseInputStream.Flush();
        }

        /// <summary>
        /// Sets the position within the current stream
        /// Always throws a NotSupportedException
        /// </summary>
        /// <param name="offset">The relative offset to seek to.</param>
        /// <param name="origin">The <see cref="SeekOrigin"/> defining where to seek from.</param>
        /// <returns>The new position in the stream.</returns>
        /// <exception cref="NotSupportedException">Any access</exception>
        public override long Seek(long offset, SeekOrigin origin)
        {
            throw new NotSupportedException("Seek not supported");
        }

        /// <summary>
        /// Set the length of the current stream
        /// Always throws a NotSupportedException
        /// </summary>
        /// <param name="value">The new length value for the stream.</param>
        /// <exception cref="NotSupportedException">Any access</exception>
        public override void SetLength(long value)
        {
            throw new NotSupportedException("InflaterInputStream SetLength not supported");
        }

        /// <summary>
        /// Writes a sequence of bytes to stream and advances the current position
        /// This method always throws a NotSupportedException
        /// </summary>
        /// <param name="buffer">Thew buffer containing data to write.</param>
        /// <param name="offset">The offset of the first byte to write.</param>
        /// <param name="count">The number of bytes to write.</param>
        /// <exception cref="NotSupportedException">Any access</exception>
        public override void Write(byte[] buffer, int offset, int count)
        {
            throw new NotSupportedException("InflaterInputStream Write not supported");
        }

        /// <summary>
        /// Writes one byte to the current stream and advances the current position
        /// Always throws a NotSupportedException
        /// </summary>
        /// <param name="value">The byte to write.</param>
        /// <exception cref="NotSupportedException">Any access</exception>
        public override void WriteByte(byte value)
        {
            throw new NotSupportedException("InflaterInputStream WriteByte not supported");
        }

        /// <summary>
        /// Entry point to begin an asynchronous write.  Always throws a NotSupportedException.
        /// </summary>
        /// <param name="buffer">The buffer to write data from</param>
        /// <param name="offset">Offset of first byte to write</param>
        /// <param name="count">The maximum number of bytes to write</param>
        /// <param name="callback">The method to be called when the asynchronous write operation is completed</param>
        /// <param name="state">A user-provided object that distinguishes this particular asynchronous write request from other requests</param>
        /// <returns>An <see cref="System.IAsyncResult">IAsyncResult</see> that references the asynchronous write</returns>
        /// <exception cref="NotSupportedException">Any access</exception>
        public override IAsyncResult BeginWrite(byte[] buffer, int offset, int count, AsyncCallback callback,
                                                object state)
        {
            throw new NotSupportedException("InflaterInputStream BeginWrite not supported");
        }

        /// <summary>
        /// Closes the input stream.  When <see cref="IsStreamOwner"></see>
        /// is true the underlying stream is also closed.
        /// </summary>
        public override void Close()
        {
            if (!isClosed)
            {
                isClosed = true;
                if (isStreamOwner)
                {
                    baseInputStream.Close();
                }
            }
        }

        /// <summary>
        /// Reads decompressed data into the provided buffer byte array
        /// </summary>
        /// <param name ="buffer">
        /// The array to read and decompress data into
        /// </param>
        /// <param name ="offset">
        /// The offset indicating where the data should be placed
        /// </param>
        /// <param name ="count">
        /// The number of bytes to decompress
        /// </param>
        /// <returns>The number of bytes read.  Zero signals the end of stream</returns>
        /// <exception cref="SharpZipBaseException">
        /// Inflater needs a dictionary
        /// </exception>
        public override int Read(byte[] buffer, int offset, int count)
        {
            if (inf.IsNeedingDictionary)
            {
                throw new SharpZipBaseException("Need a dictionary");
            }

            int remainingBytes = count;
            while (true)
            {
                int bytesRead = inf.Inflate(buffer, offset, remainingBytes);
                offset += bytesRead;
                remainingBytes -= bytesRead;

                if (remainingBytes == 0 || inf.IsFinished)
                {
                    break;
                }

                if (inf.IsNeedingInput)
                {
                    Fill();
                }
                else if (bytesRead == 0)
                {
                    throw new ZipException("Dont know what to do");
                }
            }
            return count - remainingBytes;
        }

        #endregion

        #region Instance Fields

        /// <summary>
        /// Base stream the inflater reads from.
        /// </summary>
        protected Stream baseInputStream;

        /// <summary>
        /// The compressed size
        /// </summary>
        protected long csize;

        /// <summary>
        /// Decompressor for this stream
        /// </summary>
        protected Inflater inf;

        /// <summary>
        /// <see cref="InflaterInputBuffer">Input buffer</see> for this stream.
        /// </summary>
        protected InflaterInputBuffer inputBuffer;

        /// <summary>
        /// Flag indicating wether this instance has been closed or not.
        /// </summary>
        private bool isClosed;

        /// <summary>
        /// Flag indicating wether this instance is designated the stream owner.
        /// When closing if this flag is true the underlying stream is closed.
        /// </summary>
        private bool isStreamOwner = true;

        #endregion
    }
}